WHAT IS ALPHA-LACTALBUMIN?
Also known as alpha, alpha-lac or lactalbumin, alpha-lactalbumin is one of the main protein fractions naturally occurring in milk. Alpha-lactalbumin is the most prominent protein fraction in human milk and second most prominent fraction in bovine milk. It is naturally high in the essential amino acid tryptophan, and the sulphur amino-acid, cysteine.
ALPHA-LACTALBUMIN IN INFANT NUTRITION
One of the key features of alpha-lactalbumin is its amino acid profile, which includes a relatively high tryptophan and cysteine content. The level of these amino acids in cow’s milk is around half that in human milk; however, bovine alpha-lactalbumin has a higher level of these key amino acids, thus can allow amino acid profiling of formula much closer to human milk.
Mother’s milk needs to provide all the essential amino acids for the infant’s growth and if not breastfed, the alternative nutritional source must provide these. The difference in amino acid content of human vs. cow’s milk leads to the higher protein content of infant formulas, to ensure sufficient amino acid intake. Tryptophan and cysteine are key, as the level of both amino acids in cow’s milk is around half that in human milk; however, using alpha-lactalbumin compensates for this and allows amino acid profiling of formula closer to human milk.
ALPHA-LACTALBUMIN'S IN ADULT NUTRITION
Tryptophan is the precursor of serotonin, which is a neurotransmitter and functions as the precursor to melatonin (hormone involved in the sleep-wake cycle). Serotonin exerts multiple effects and is popularly thought to be a main contributor to feelings of well-being and happiness. It is implicated in mood, cognitive performance, sleep regulation, and weight management.
Serotonin is synthesized from tryptophan (TRP) and brain serotonin concentrations rise with tryptophan intake (Markus et al, 2000). Additionally, it is important the ratio between tryptophan and large neutral amino acids (LNAA) is high, as they both use the same amino acid transporter across the blood brain barrier (figure below). (Other ways to manipulate TRP uptake include increasing carbohydrates, as the associated insulin response then encourages uptake of LNAAs in the muscle tissue, thus favorably altering the plasma TRP:LNAA).
As little as 500mg has been shown to enhance the plasma TRP:LNAA levels by 48% against placebo, in both low- and high-stress vulnerable subjects.
A decline in serotonin activity in the brain is involved in the development of depressive mood, whereas increased brain serotonin may help improve the ability to cope with stress. In the same study as above, Markus et al investigated the impact of the drinks on depression scores. The supplements were given in 2 drinks – one at breakfast, one at lunch – and the subject underwent experimental stress in the afternoon. In high stress-vulnerable individuals, there was a reduction in depression scores.
ALPHA-LACTALBUMIN AND COGNITIVE PERFORMANCE
Cognitive performance often declines during exposure of chronic stress. The negative effect of chronic stress may be mediated by reduced brain serotonin function. Thus, a diet-induced increase in the serotonin precursor tryptophan help increase brain serotonergic activity levels and improve cognitive performance. Studies have shown benefits of alpha supplementation on cognitive performance, including:
Faster reaction time with 500mg TRP from alpha compared to 300mg TRP from caseinate, in high stress vulnerable adults (Markus et al, 2002).
Improved memory after consumption of an alpha-lactalbumin diet compared to a caseinate diet.
ALPHA-LACTALBUMIN AND SLEEP?
Benefits on sleep quality have been observed from both alpha supplementation and tryptophan supplementation. These include:
In those with mild sleep complaints, alpha-lac (providing 1.9g TRP) was found to reduce morning sleepiness score, implying a better night’s sleep (Markus et al 2005).
Reduce sleep latency (time to get to sleep) in those who normally have a longer sleep latency, with 1g TRP supplementation.
Pre-bed protein feeding is generally recognized to enhance muscle re-synthesize and growth, and while most work has been done using casein, there is no reason to believe whey protein would not be just as effective (Trommelen and Loon, 2016).
ALPHA-LACTALBUMIN AND WEIGHT MANAGEMENT
Although the effects of dietary protein and whey proteins are well known, studies comparing different protein types or fractions are scarce. However, it has been demonstrated that alpha-lactalbumin has an increased effect on satiety compared to other protein sources such as WPI and it is down to more than just the TRP (Nieuwenhuizen 2008; Pilvi et al, 2009; Veldhorst et al 2008). More work is required in this area.
WHAT APPLICATIONS DOES ALPHA-LAC WORK IN?
Alpha-lactalbumin works well in a wide range of applications, including ready-to-mix (RTM) shakes, ready-to-drink (RTD) beverages, bars, cookies and more.